This one is from the small batch of 1956 with Seamaster misspelled on the caseback "Seemaster". There are a couple other identical ones found within a very narrow serial number range.

Plus:
Clean original movement with original balance and regulator
Keeps good time
Chronograph works fine and resets to zero.
Attractiva patina dial
Case in good condition

Minus
Replaced subdial hand
Hour counter creep
Caseback does not sit tightly. It does not come off but can rotate slightly since there is at present no gasket, maybe the right gasket is needed and will solve the issue?
TZ grading 80%
Located in Stockholm.
Head only